1. Field of the Invention
The present invention relates in general to filters for fluids. In particular, the present invention relates to an improved air filter for heating, cooling, ventilation and other equipment, which may be fabricated on site.
2. Description of the Related Art
It has been known for many years to employ air filters for a variety of equipment, most notably heating, cooling and ventilating equipment. Such filters typically take the form of a rectangular frame which serves to hold a filter medium therein. The filter medium may be any of a variety of substances including fiberglass, expanded paper or other materials which tend to trap particulates entrained in a gas stream which passes through the medium.
As the gas stream is directed to flow through the filter medium, pressures are exerted upon the medium due to this air flow. To ensure that the sometimes fragile medium is not removed from its peripheral frame due to this pressure, it has been known to provide a protective screen on one or both sides of the filter. This protective screen typically takes the form of a lattice having a large number of openings therein, which provide support to the filter medium while causing as little impediment to air flow as is possible.
During normal maintenance or during repair work upon the equipment containing such air filters, it is often necessary to replace the air filter. However, air filters are often designed to be unique to the particular piece of equipment, with little standardization of sizes. As such, it is often difficult to determine the particular size of air filter needed for a particular piece of equipment.
Since the vast majority of equipment containing such air filters is large and bulky, it must be serviced on site. This necessitates the worker carrying a large number of air filters of different sizes to the site, or determining the particular size of filter on site and then ordering that size air filter brought to the site. This arrangement is both inefficient and costly.